This invention relates to a document transfer device for transferring a document to a document stop reference position disposed at one end of a contact glass of an image reading apparatus, and an image reading apparatus having the same. Especially, this invention relates to a document transfer device having a transfer device for transferring a document to a document stop reference position disposed at one end of a contact glass and a contact glass cover for covering a remaining portion of the contact glass adjacent to the transfer device, and an image reading apparatus having the same.
Heretofore, as a document transfer device of this type, for example, there has been known a document transfer device having a structure as shown in FIGS. 20 and 21 (refer to Japanese Patent Publication, TOKKAI No. 06-90322).
The document transfer device includes a transfer belt 53 of a transfer device 50 covering a part of a contact glass 55, and a contact glass cover 41 (a main body of the contact glass cover) disposed adjacent to the transfer belt 53 to cover a remaining portion of the contact glass. A pick-up roller 23 takes the document mounted on a supply tray 11, and a supply roller 24 and a separation roller 25 separate the document one by one. Then, each separated sheet abuts against a nip point between a stopping resister roller 26 and a resister press roller 27 to thereby remove skew of the document. The transfer belt 53 transfers the document to a reference position P1, where reading is carried out. In the case that a register sensor S2 recognizes the document as a short size (a S-size), the document is transferred to the reference position P1 by clockwise rotation of the transfer belt 53 through forward rotation of a motor (not shown) as a driving source and then stopped. In the case the register sensor S2 recognizes the document as a long size (a L-size), the document is transferred by the clockwise rotation of the transfer belt 53 through the forward rotation of the motor. Then, the document stops after a predetermined time after a document discharge sensor S3 detects a leading edge of the document. At this time, a trailing edge of the document has passed through an adjacent portion R. Then, the document is transferred in a reverse direction by the counter-clockwise rotation of the transfer belt 53 through the reverse rotation of the motor. At this time, as shown in FIG. 21, link members 44 are rotated counter-clockwise by the reverse rotation of the motor M2 through a register roller shaft 48, a drive arm 46 and an engaging pin 45. Accordingly, a contact glass cover main body 41 is rotated around a supporting shaft 42 as a pivot and opened to the left side thereof to make a predetermined space “g”. Then, the document is inserted into the space “g” and its reverse transfer is stopped after a very short time. The document is transferred forward by the transfer belt 53 through the forward rotation of the motor M2 and stopped at the reference position P1. Further, at this time, the contact glass cover main body 41 falls downward through clockwise rotation of the drive arm 46 and link members 44 by the forward rotation of the motor M2. With the structure as described above, a transfer distance to the reading position of the small-size document, which is used very often, is reduced to thereby shorten a transfer time.
However, in the above-stated apparatus, in the case of handling the long-size document, after the document is transferred forward, it is moved in reverse and then again transferred forward (switch-backed) to the reference position. Therefore, a transfer distance becomes very long to thereby take a long time.
In view of the above problem, the present invention has been made and an object of the invention is to provide a document transfer device, in which the transfer time of the short-size document is shortened and, at the same time, the transfer time/distance of the long size document is shortened with a simple structure.
Another object of the invention is to provide an image reading apparatus having such a document transfer device as described in the first object, in which an entire process time is shortened.
Further objectives and advantages of the invention will be apparent from the following description of the invention.